Fast-growing sunspot AR3842 erupted on Oct 1st (2220 UT), producing the second-strongest solar flare of Solar Cycle 25. The X7.1-category blast caused a shortwave radio blackout over Hawaii and hurled a CME into space. A preliminary NASA model predicts it will hit Earth on Oct. 5th. Stay tuned for the geomagnetic storm forecast.

Imagine a waterfall made of hot plasma falling from a precipice tall enough to swallow Earth five times. Here it is:

Dutch photographer "Neo" captured this movie on August 28th. "For three days I've been watching these prominences around the edge of the active sun," he says. "The plasma did not stop falling for a moment."
Plasma falls have been seen on the sun many times before, yet researchers still don't fully understand them. One big mystery is how fast they fall. The sun's gravity is powerful, but not powerful enough to pull the plasma down so quickly through the thicket of solar magnetic fields.
Nuclear engineers would like to figure out how this happens, because it also happens on a smaller scale in fusion reactors, frustrating their efforts to sustain an energy-producing reaction. Studies of plasma falls on the sun could lead to practical breakthroughs here on Earth.
https://spaceweather.com/

Active sunspot AR3777 just produced its most powerful solar flare yet--an X1.3-class explosion on Aug. 8th (1935 UT). NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash:

Radiation from the flare ionized the top of Earth's atmosphere and caused a shortwave radio blackout from North America to the Hawaiian islands. Mariners and ham radio operators may have noticed loss of signal below 30 MHz for as much as an hour after the flare.
Of greater interest is a possible CME. The US Air Force is reporting a strong Type II radio burst. This type of natural radio emission comes from shock waves at the leading edge of a fast CME. Confirmation awaits fresh data from SOHO coronagraphs. Stay tuned.
https://spaceweather.com/

Great sunspot AR3664 has hurled an astonishing five CMEs toward Earth. They're all in this frenetic 2-day coronagraph movie from the Solar and Heliospheric Observatory (SOHO):

The two bright objects are Jupiter (left) and Venus (right). The CMEs will miss those planets and hit Earth instead.
According to a NOAA forecast model, the first three CMEs could merge for form a "Cannibal CME." Cannibal CMEs form when fast-moving CMEs overtake and gobble up slower CMEs in front of them. Internal shock waves created by such CME collisions do an good job sparking geomagnetic storms when they strike Earth's magnetic field.
The Cannibal CME is expected to arrive on May 11th. It alone could spark a strong (G3) geomagnetic storm. With two more CMEs following close behind, storm levels could become extreme (G4), sparking auroras at mid- to low-latitudes across Europe and the USA.
https://spaceweather.com/

Last week, Andreas Kohlmann of Samnaun, Switzerland, looked up and saw a 22° sun halo caused by ice crystals floating over the snowy landscape. His iPhone11 photo of the phenomenon captured something sky watchers often overlook--the 'hole in the sky' effect:

The sky inside the halo is darker than the sky outside, creating a large but subtle disk of partial darkness around the sun. It exists because the ice crystals scatter light at least 22° away from the sun. "No light is refracted through smaller angles, so the area inside the halo is dark," explains retired atmospheric optics expert Les Cowley.
"Most rays are deflected through angles near to 22° to form the bright inner edge of the halo," he continues. "Red light is refracted less strongly than other colors, so the halo's inner edge is red hued."
The 22° sun halo is the most common of all sun halos. The next time you see one, put on sunglasses to reduce the glare. You may see your own 'hole in the sky.'
https://spaceweather.com/

For the second time in less than a week, energetic solar protons are raining down on Earth's upper atmosphere. Forecasters call this a "solar radiation storm." Today's storm (near category S2) is rich in "hard protons" wiith energies greater than 50 MeV. It is causing a shortwave radio blackout inside the Arctic Circle and speckling the cameras of some Earth-orbiting satellites.

The plot above shows storm data recorded by NOAA's GOES-18 satellite in Earth orbit. Sensors on the satellite are counting energetic protons as they pass by en route to Earth. Triggered by an explosion near the sun's southwestern limb (inset), this storm could last for another 24 hours.
https://spaceweather.com/

The sun is partying like it's 2002. That's the last time sunspot counts were as high as they are now. The monthly average sunspot number for June 2023 was 163, according to the Royal Observatory of Belgium's Solar Influences Data Analysis Center. This eclipses every month since Sept. 2002:

Solar Cycle 25 wasn't expected to be this strong. When it began in Dec. 2019, forecasters believed it would be a weak cycle akin to its immediate predecessor Solar Cycle 24. If that forecast had panned out, Solar Cycle 25 would be one of the weakest solar cycles in a century.
Instead, Solar Cycle 25 has shot past Solar Cycle 24 and may be on pace to rival some of the stronger cycles of the 20th century. The last time sunspot numbers were this high, the sun was on the verge of launching the Great Halloween Storms of 2003, which included the strongest X-ray solar flare ever recorded (X45), auroras as far south as Texas, and a CME so powerful it was ultimately detected by the Voyager spacecraft at the edge of the solar system.
www.spaceweather.com

Before the launch of the Solar and Heliospheric Observatory (SOHO) in 1995, astronomers had never seen anything like this. Behold, a solar storm passing directly in front of the Pleiades:

SOHO recorded this rare conjunction on May 21st. An erupting filament of magnetism near the sun's north pole propelled the CME into space just as the Seven Sisters were passing by. Electra, Taygete, Maia, Celaeno, Alcyone, Sterope, and Merope spent nearly three hours shining through the translucent solar storm.
When SOHO left Earth almost 30 years ago, it carried the first realtime coronagraph into space. Coronagraphs are devices that create an artificial eclipse, blocking the glare of the sun to reveal nearby stars, planets, and comets. No telescope on Earth could see something as faint as the Pleiades only a few degrees from the sun, but SOHO does it all the time.
https://spaceweather.com/

"It was a brilliant beautiful eclipse," reports eyewitness Eliot Herman. "We observed on a small island in the Montebello group off the coast of Australia very close to the center line." This is what he saw:

"Paul Maley made the arrangements and got the permissions," he adds. "There were only 15 of us, and it was really special to have the island to ourselves so far from civilization."
Maley was taking pictures alongside Herman. "This was my 82nd solar eclipse," Maley says. "At our location the eclipse lasted only 55 seconds, but it was spectacular. The sky was super clear following the recent passage of cyclone Ilsa." The exceptional transparency allowed him to capture several red prominences around the rim of the sun:

Now a marine conservation reserve, the islands were the site of three British atmospheric nuclear weapons tests in 1952 and 1956. Herman brought a Geiger counter to their observation site. "I tested a bunch of rocks and fragments but nothing was 'hot,'" he says. "The Montebellos are quite isolated. It was remarkable to have a chance to be here."
Today's hybrid eclipse was the first in almost 10 years, making it a rare event. Hybrid eclipses are a mixture of two types: annular and total. This one began as an annular eclipse over the Indian Ocean, transitioned into a total eclipse over western Australia, and ended as an annular eclipse over the South Pacific: map.
www.spaceweather.com

Something rare and strange happened last month. On Feb. 23rd, growing sunspot AR3234 produced an M-class solar flare. It was nearly midnight in Florida when the explosion occurred, so you'd expect no one there to notice. On the contrary, in the community of High Springs, FL, amateur radio astronomer Dave Typinski recorded a strong shortwave radio burst.
"You CAN see the sun at midnight in Florida... sometimes," says Typinski. This is what his instruments recorded while the flare was underway:

A double wave of static washed over Florida, filling the radio spectrum with noise at all frequencies below 25 MHz. "The Sun was 69° below the horizon when this happened," he marvels.
How is this possible? The entire body of our planet was blocking the event from Typinski's antenna. It's called "antipodal focusing". First postulated by Marconi more than 100 years ago, antipodal focusing is a mode of radio propagation in which a signal starts out on one side of the planet, gets trapped between Earth's surface and the ionosphere, and travels to the opposite hemisphere. Waves converging at the antipode can create a surprisingly strong signal.

"This is the second or maybe third midnight solar radio burst I've seen in ten years, but it's by far the strongest," says Typinski. "The previous events happened at the height of Solar Cycle 24. They're quite rare."

Pause: Yes, solar flares can produce radio signals. Typinski's midnight burst was a "Type V", caused by streams of electrons shooting through the sun's atmosphere in the aftermath of the flare. Plasma waves rippling away from the streams emited intense bursts of natural radio static. The burst was first observed in broad daylight at the Learmonth Solar Observatory in Australia, then it curved around Earth to reach Typinski.

"This propagation mode was used during the Cold War," notes Typinski. "The U.S. would park a SIGINT ship in the south Pacific to grab signals from the Eastern Bloc. The Soviets probably did the same thing, parking in the southern Indian ocean."
Turns out, this method of spying works for radio astronomers, too. Would you like to record an event like this? NASA's Radio JOVE program makes it easy. Off-the-shelf radio telescope kits allow even novices to monitor radio outbursts from the sun, which are becoming more frequent as Solar Cycle 25 intensifies.
www.spaceweather.com

It seemed like sunspot AR3088 would never stop exploding. Over the past four days, the strangely-magnetized active region produced more than a dozen M-class solar flares:

Each X-ray peak in the graph above produced a corresponding shortwave radio blackout on Earth. No part of our planet was untouched.
More than half of the explosions also produced a coronal mass ejection (CME). Earth dodged them all. Only one and maybe two delivered glancing blows of no consequence. All the rest sailed harmlessly into space.
The simple reason why: AR3088 was never facing Earth. Most of the explosions occurred while the sunspot was approaching or even rounding the sun's western limb.

This movie from NASA's Solar Dynamics Observatory is a good example. It shows a flare from AR3088 on Aug. 29th partially eclipsed by the edge of the sun. The explosion registered M9 on GOES satellite X-ray sensors, but the uneclipsed flare was probably much stronger--perhaps even an X-flare.
If the sunspot had been facing us, we might now be experiencing strong geomagnetic storms with spectacular low-latitude auroras. Maybe next time...
https://spaceweather.com/

Photographers consider themselves lucky when they catch a green flash. The sunset emerald ray is so rare, it was once thought to be a fable. Now imagine the odds of catching a triple green flash. James W. Young did it last night while standing on Oregon's Cannon Beach:

"The setting sun produced a green flash which split into three layers," marvels Young. "I photographed them using a 1120mm telephoto lens with a Canon 1Dx Mark II camera."
This is a sign of very strong temperature inversions (warm air above cold) over the Pacific Ocean. Strong inversions produce 'ducts'. Rays from the setting sun get trapped in these ducts, bouncing up and down and traveling long distances in layers sometimes only a few inches thick. A trio of ducts split the green flash into a stack of three. You can actually see the ducts edge-on in Young's picture--a marvel, indeed.
https://spaceweather.com/

September 20, 2021 / Dr.Tony Phillips - NASA

Sept. 24, 2021: No solar storms? No problem. Earth has learned to make its own auroras. New results from NASA’s THEMIS-ARTEMIS spacecraft show that a type of Northern Lights called “diffuse auroras” comes from our own planet – no solar storms required.

Diffuse auroras look a bit like pea soup. They spread across the sky in a dim green haze, sometimes rippling as if stirred by a spoon. They’re not as flamboyant as auroras caused by solar storms. Nevertheless, they are important because they represent a whopping 75% of the energy input into Earth’s upper atmosphere at night. Researchers have been struggling to understand them for decades.

Above: Diffuse auroras and the Big Dipper,
photographed by Emmanuel V. Masongsong in Fairbanks, AK

“We believe we have found the source of these auroras,” says UCLA space physicist Xu Zhang, lead author of papers reporting the results in the Journal of Geophysical Research: Space Physics and Physics of Plasmas.

It is Earth itself.

Earth performs this trick using electron beams. High above our planet’s poles, beams of negatively-charged particles shoot upward into space, accelerated by electric fields in Earth’s magnetosphere. Sounding rockets and satellites discovered the beams decades ago. It turns out, they can power the diffuse auroras.

The video below shows how it works. The beams travel in great arcs through the space near Earth. As they go, they excite ripples in the magnetosphere called Electron Cyclotron Harmonic (ECH) waves. Turn up the volume and listen to the waves recorded by THEMIS-ARTEMIS:

Above: A great electrical circuit in space powering diffuse auroras. ECH waves were sonified by NASA’s HARP (Heliophysics Audified: Resonances in Plasmas) software.

ECH waves, in turn, knock other electrons out of their orbits, forcing them to fall back down onto the atmosphere. This rain of secondary electrons powers the diffuse auroras.

“This is exciting,” says UCLA professor Vassilis Angelopoulos, a co-author of the papers and lead of the THEMIS-ARTEMIS mission. “We have found a totally new way that particle energy can be transferred from Earth’s own atmosphere out to the magnetosphere and back again, creating a giant feedback loop in space.”

According to Angelopoulos, Earth’s polar electron beams1 sometimes weaken but they never completely go away2, not even during periods of low solar activity. This means Earth can make auroras without solar storms.

The sun is currently experiencing periods of quiet as young Solar Cycle 25 sputters to life. Pea soup, anyone?  [Note: Solar Cycle 25 is accelerating.  MS}

End Notes:

(1) Why do these electron beams exist? Earth’s magnetosphere is buzzing with energetic particles. Many of them are captured from the solar wind. When these particles strike the top of Earth’s atmosphere (the ionosphere), they dislodge electrons. Electric fields, which form naturally in Earth’s spinning magnetosphere, grab the liberated electrons and accelerate them skyward in collimated beams.

(2) Why don’t the beams ever go away? Short answer: because the solar wind never stops blowing. Even when the sun is quiet, Earth’s magnetosphere is jostled and energized by the ever-present solar wind. As a result, electrons are always being knocked off the top of Earth’s atmosphere as described in Note #1. Although solar storms are not required for this process, solar storms can help. For instance, when a CME strikes Earth’s magnetosphere, the contents of the magnetosphere become extra-energized. Lots of particles furiously strike the top of Earth’s atmosphere, liberating even more electrons than usual. Earth’s electron beams can thus become super-charged. When the storm subsides, the electron beams may weaken, but they never vanish because even the quiet sun produces solar wind.

References:

Zhang, X., Angelopoulos, V., Artemyev, A. V., Zhang, X.-J. (2021), Beam-driven ECH waves: A parametric study, Phys. Plasmas, 28, 072902, https://doi.org/10.1063/5.0053187

Zhang, X., Angelopoulos, V., Artemyev, A. V., Zhang, X.‐J., Liu, J. (2021). Beam‐driven electron cyclotron harmonic waves in Earth’s magnetotail. Journal of Geophysical Research: Space Physics, 126, e2020JA028743. https://doi.org/10.1029/2020JA028743s

https://spaceweatherarchive.com/2021/09/20/earth-can-makes-its-own-auroras/